Centrifuge



Patented Dec. 2z, v193e UNITED STAT-Es PATENT GFFICE cEN'rnIFUGn lians Olor Lindgren, Appelviken, Sweden, assignor to The De Laval Separator Company, New

York, N. Y., a corporation of New Jersey Application. January 2o, 1933, serial No. 652,746

` En Sweden'January 23, 1932 17 cannaA (01.,233-11) In closed centrifugesin which the liquid is y supplied to and discharged'from the centrifugal vbowlthrough xed pipe lines which are tightly kind, the material of the packing is exposed to.

connected to the bowl by. packing boxes of some the riskof serious damage if the centrifuge be rotated for some length of time with no liquid in the packing boxes. Owing to the very high number of revolutions of the bowl, which causes a in very high relative velocity between the tightening be transmitted per time unit, and a considerablev energy, which must be applied during the starting period, but owing to the capacity-of the driving motor and the resistance of the transmission' members, only a limited arriount of energy can time is therefore required to transmit the necessary'amount of energy to the centrifugal bowl. As compared with a centrifugal pump or the like, the starting timeis therefore many times longer and may. amount to about ten minutes. Another Vcircumstance which should not be overlooked is' the fact that the liquid must not be fed into the centrifuge until it has reached its full number of revolutions, since the liquid is not treated in 'a satisfactory manner unless the centrifugal force has attained its full value. A centrifugal pump,

on the other hand, must be filled with liquid at' the/start in order to put it into operation. With a pump it is therefore not necessary to take any special measures to avoid the risk of the packings being damaged by too high a temperature, but with a centrifuge having similar packings the conditions are quite the reverse.' With a centrifuge,

special steps must be taken in order to avoid damage to packngs While the centrifuge is gradually speeding up to its normal operating speed.

'I'he present invention comprises a method and means of protecting the material of the packing againstthe risk of becoming damaged by the frictional hca't generated during the starting opera tion by effectively cooling the packing boxes during the whole or the greater part'ofsuch starting operation. 'A sumcient cooling can be effected if the separation liquid lwhich is normally contained in the packing box is present therein at the start. It isVV also possiblel to bring about the cooling by means of a special liquid, which may either be fed to 'the'packing boxes before the start of the centrifuge in some suitable mannen-for instance by a cock or the like, or which may be caused to circulate through the packing boxes bymeans of suitable devices. The best method of eecting vthe required' cooling is, however, in most cases, to make the liquid to be separated stream in a closed circuit through the centrifuge before, at, or immediately or soon after the start. In a centrifuge of the type referred to, it is necessary to force the liquid through the centrifugal bowl by means of some pumping device. The circulation mentioned may be brought about simply by starting the pump' at the right moment after a special return pipe has been opened. Itis not, of course, quite necessary that the circulationof the liquid should begin at the start -of the centrifuge, since no dangerous generation of. heat takes place at. the tightening surfaces of the packing boxes while the machine rotates at a comparatively low speed. As the-speed increases, the heat generation per time unit also increases, so that the temperature. tends to rise progressively. In any case the cooling process must be in operation before the centrifuge has 'attained its full R. P. M.

When a limited quantity of liquid is introduced into the packing boxes at the start, the xed pipes connected with the centrifuge must be arranged in such a manner close tothe centrifuge that the cooling liquid cannot discharge therethrough.. Closest to the centrifuge, therefore, the pipes should extend upward from the machine.

v'Ihere is the same risk of a deterioration of the tightening material in case the supply of liquid being treated in the centrifuge should be interrupted, for any reason, after the centrifuge has been started. It is often necessary, particularly in dairies, to so interrupt the operation of the machine. The present invention also comprises a method and means for cooling the packing boxes during such interruption. The specific embodiments of thev inventionv hereinafter described insure a sufficient circulation of liquid through the centrifuge upon ,cessation or interruption of the supply of such liquid treated in the centrifuge as well as during the starting operation.

' The full object of the invention may be attained in many different ways. For instance, a return pipe may be arranged from one or more of the outlets of the centrifuge to its inlet. As entrifuges of this type usually are provided with liquid, for instance, water a pump4 which forces the liquid through the vcentrifuge under a comparatively high pressure, 'the return pipe should of course be connected to the inlet side of the pump. A valve may arranged infv the 'return pipe which should normally be closed but may be opened when required.

Such a simple device would, however, scarcely lost. While the present invention, in its broader aspect, contemplates the employment of a return pipe that is maintained open, its preferred embodiments include means whereby a cooling liquid-is automatically fed into the centrifuge `and made to circulate therethrough When,`for Aany reason, the normal supply 'of liquid under treatment is interrupted or substantially reduced. On such occasions the pressure in thev supply pipe of the centrifuge drops towards nil. In the preferred embodiments of the invention, there yis'fprovided a regulating apparatus which reacts to -the pressure and in turn controls a valve or valves for the cooling liquid, which may or va special cooling from a water pipe. In the former case the regulating apparatus, at the proper time,I automaticallyopens'valves consist of separated liquid in the pipes which run from the outlet pipes of the centrifuge t'o the inlet-of the centrifuge. lIn the latter case, the regulating apparatus opens a valve, for instance to the water pipe,.so that water circulates through the centrifuge. In this case the regulating apparatus may also be arranged to shut the outlet pipes of the centrifuge and open special outlets for the cooling' water.

In another embodiment of the invention there is provided, inthe neighborhood of the centrifuge, a. container from which liquid is, at the proper time, automatically fed into the centrifuge by the regulating apparatus. 'Ihe container may stand by itself, or it may be combined with one of the outlet pipes of the centrifuge in such a manner that already centrifugated liquidis utilized for the cooling. In the latter case, and particularly when no container isprovided, it is desirable to interpose in the conduit for cooling liquid aA cooler which lowers the temperature of the liquid Ibefore it again enters the centrifuge.,

Without re-c'ooling, the cooling liquid would slowly be'heated by the frictional heat generated in the packing boxes to such a high temperature that its cooling-quality wouldl be lost.

The accompanying drawings show a number of different embodiments of the invention.

Figs. 1, 2 and 3 are diagrams illustrating different embodiments of the invention.

Fig. 4 is a vertical sectional view of a modification wherein the valves and the regulating apparatus therefor are built in a unitary structure.

Figs. 5 and 6 are respectively horizontal and vertical sections through another'similar unitary structure. y

Figs., '7 and 8 are respectively horizontal and vertical sections through still another similar unitary structure Fig. ais-"a vertical sectional view through a also bev When the'pressure in the .the valve I I.

with a level outlet over which the l ing container may be connected typical packing box for a centrifuge of the closed type. y l In the embodiment shown in Fig. l, a pump I forces the liquid through a pipe-2 into' the centrifuge 3, from which two separated components discharge, for "instance cream and skim milk, through'pipelines 4 and 5 respectively, the latter, for instance, To the pipe line -5 which part of the skim milk may be led back to the inlet side of the pump. v

y In the embodiment shown in Fig. 2 one or more return pipes are automatically opened when the feed of liquid to be treated falls below normal. The supply pipe 2 of the centrifuge communi- 1 with a regulating apparatus control of the valves for the cates by'a pipe line 8 whichv effects lthe 'being intended for the milk. .i is connected a pipe 6 through' cooling liquid. 'I'he Aregulating 'apparatus con- 'I sists, for example, of. a cylinder provided with a piston 9 acting on valves I 0 and II in pipe lines I2 and I3 respectively. 'I'he pipe lines I 2 and I3 are connected to pipe lines 4 and 5 respectively. -The pipe lines I2 and I3 open over a funnel I 4 connected with the pipe line 60. As long as the pressure in the'pipe lines 2 and 1 respective] is normal, the piston 9 is maintained in its upper position and ,the valves I0 and II are closed. pipe line 2 drops, the piston 9 moves downward under the influence of a counter-weight I5 positioned on the leverof I3 are then opened so be supplied to the through the funnel this way a continuous circulation of liquid through the vpacking boxes of the machine is insured. As the cream and the skim milk stream down into the funnel in free jets, it is impossible for the cream to enter the skim milk outlet, or the reverse. With this arrangement there is obtained the additional advantage that the jets inthat separated liquid can pump and the centrifuge 'dicat'e an'y interruption in the milk supply, as

they are well visible. Anyother device acting in the same manner may of 4course be substituted for the regulating devices 8 and 9. Instead of a piston, a membrane or slide, of the character of those hereinafter. described,may be used.

'Ihe valves in pipe lines I2 andV I4 and the pipe line 60. In

In the embodimentshown in Fig. 3, the cool- I ing liquid is taken from a skim milk container I6, which may be positioned on a higher level than the centrifuge. The container is connected to the discharge pipe 5 for skim.milk from the centrifuge and to a pipe line I'I, connected with the pump I. In pipe line I1 is interposed a cooler I8 and a valve I I. 'Ihe cream discharge pipel 4 is provided with a valve I9. Through suitable mechanical connections 6I the regulating apparatusS closes valve I9 at the same time that it opens valve II. The container I6 is provided skim milk discharges to the pipe 20. 'I'he level in the container I6 is thus constant as long as liquidls not removed therefrom and circulated through the centrifuge, thereby insuringthe maintenance of a sucient quantity of skim milk in the container if an interruption should occur in the s upply of'whole milk. A similar liquid accumulat- With the cream Outlet in substitution for, or in addition to, the

container I6. It is not necessary to close the for some length of time the container I6 may become quite empty if the cream outlet 4 be open. The automatically shut valve |9, although generally not necessary, is decidedly advantageous.

It is possible, and also advantageous, to associate, in a unitary structure, theregulating apparatus 8 and the valves l0, and |9. Of these valves the valve l0, which controls the return flow of the cream, vmay often, for instance in purifiers, be dispensed with, so that only a part corresponding to the valve need be retained. Such an arrangement is shown in Fig. 4. The apparatus comprises a membrane 2|, suitably of heavy rubber, and fixed between two sections of a housing 22 and 23. The upper side of the membrane is subject to pressure from the supply pipe 2, which communicates with the membrane through a -pipe line and the channel 24 in the housing. Beneath the member is a spring 25, which is in contact with the membrane through a part 26 and tends to lift it against the pressure from the pipe 2. In the gure, the membrane is in the position that it occupies during normal operative conditions, in which position the superior pressure in the pipe 2 shuts the orifice of a nozzle 21 in the housing, the lower end of which nozzle is connected with the outlet pipe of the centrifuge. The throughilow area of the nozzle may be varied by means of a screw 28. When the pressure in the channel 24 disappears or is reduced to a predetermined degree, the membrane 2| is forced upward by the spring 25 so that the nozzle 21 is brought into communication with a channel 29,I which is connected with the inlet side of the pump Thereby a circulation of liquid is established through the packing of -the centrifuge.

safest, to provide for a liquid circulation also inthe cream passage. This may be effected by opening a return pipe from the cream outlet pipe as set forth in the description of Fig. 2. Figs.

5 and 6 showl automatically operating valve mechanism for establishing such return passages bothA for cream and skim milk. The valveconsists of a cone-shaped rubber capsule 30, which also serves as a. membrane and which is pressed against grooves 3|, 32 and 33 in a cone-shaped valve housing 34 by the pressure from the pipe 2 transmitted through a channel 35. The groove 3| opens into a channel 36, which is designed to be connected with the inlet of pump I. The grooves 32 and: 33 communicate with the skim milk and cream outlets respectively. The capsule may suitably be lled up or strengthened by a solid body 31 having the same shape as the valve housing. -A spring 38 is adapted to move the capsule from the grooves 3| to 33 when the -pressure in the channel 35 disappears or is re` lar groove 43 in the slide, between` grooves 32 and 33 and channel 39.

While the described embodiments of the invention are adapted to automatically maintain a circulation of cooling uid through the packing boxes of the centrifuge whenever the supply of liquid to be separated or puried isbelow a predetermined minimum, either when the centrifuge is speeding up preparatory to admitting the liquid to be treated, or when there is an interruption in, or cessation of, the supply of liquid to be treated, it is possible, although much less desirable, to control the admission and circulation of liquid, during either or both, of these periods,

entirely manually. This may be done in differ ent ways. For example, in Fig. 1 I have shown manually operable valves 10, 1| and 12 on pipes 5, 4 and 6 respectively. ADuring speed up of the centrifuge, valves 10 and 1| may be closed and valve 12 opened. vAfter the centrifuge has attained the speed at which it is desirable to admit liquid to be treated, valve 12 is closed and valves 10 and 1| are opened. If it is desired that the cooling liquid shall be some other liquid than that to be treated, such cooling liquid may be supplied through a pipe 14 controlled by a valve 13. In either operation an endless circulation of cooling liquid will be maintained through pipe 2, the packing boxes of the centrifuge and pipe 6 back to pump A cooler, like that shown at |8 in Fig. 3, should be interposed in pipe 6.

Centrifuges wherein the discharging liquids iiow through packing boxes are well understood in the art and need not be described in detail. In Fig. 9 such packing boxes, adapted to "closed centrifuge, are shown. Through the neck of ther separator bowl is discharged the lighter separated constituent into the pipe 4 vcommunicating with a space containing packing 84. 'Ihrough channels 8| communicating with the peripheral portion of the bowl is discharged the heavier separated constituent into a chamber 82 containing packing 85 and communicating withthe pipe 5. The specific pack'ng box shown in this figure forms the subject matter of an application led by me September 18, 1931, Serial No. 563,540, now matured into Patent No. 2,002,954, datedMay What I claim and desire to protect by Letters Patent is: l

1. The combination with a centrifuge provided with an inlet and an outlet and comprising packing means with which outflowing liquid con' tacts, of 4a supply pipe for liquid to be separated an-auxiliary pipe adapted to convey a cooling liquid, both said pipes communicating with the packing means of the centrifuge, and means controlled by the pressure in the supplyv pipe to maintain said auxiliary pipe closed during normal flow toward the centrifuge of liquid to be treated and to open said auxiliary pipe to admit cooling fluid to the centrifuge when the input of liquid to be treated falls below a desired minimum, thereby insuring cooling of the tightening surfaces between rotary. and stationary parts in the packing means while the separator is operating during the period of reduced or no inflow of liquid to be treated.

2. The combination with a centrifuge provided with an inlet and an outlet and comprising packing means with which outowing liquid contacts, of a pipe adapted to convey a coolingr liquid and communicating with the packing means of the centrifuge, and means to maintain said pipe closed during normal iow toward the centrifuge of liquid to be treated and to open said pipe to admit cooling fluid to the centrifuge when the input of liquid to be treated falls below a desired minimum, thereby insuring cooling of the tightening surfaces between rotary and stationary parts in the packing means while the separator is operating during the period of reduced or no iniiow of liquid to be treated, said means comprising a regulating apparatus connected with both the centrifuge inlet and said cooling liquid pipe and adapted to be controlled by the pressure of liquid flowing toward the centrifuge.

3. The combination with a centrifuge, an inlet pipe for conveyance -to the centrifuge `of liquid to be treated, an outlet from the centrifuge and packing means with which outiiowing liquid contacts, of a return flow pipe connecting said outlet with said inlet; a valve in said return flow pipe, and a regulating apparatus connected with both the valve `in the return iiow pipe and the cenrifuge inlet pipe and operable by the pressure in said inlet pipe to control the opening and closing of said valve.

centrifuge for respectively heavier and lighter separated liquids, and packing means with which outfloWing liquid contacts, of a return oW pipe Vconnecting one of said liquid outlets with the separator inlet, a valve in said return ow pipe and a valve controlling the outlet for the other liquid and means controlled by the opening of the first named Valve to close the second named valve.

5, The combination with a centrifugal separator, of an inlet pipe for conveyance vto the separator of liquid to be separated, outlets from the centrifuge for respectively heavier and lighter separated liquids, and packing means with which outowing liquid contacts, of a return flow pipe connecting one of said liquid outlets with the separator inlet, a valve Vin said return flow pipe, and a regulating apparatus connected both with said valve and said inlet pipe and adapted to control the operation of said valve by the rpressure of liquid in said inlet pipe.

6. The combination with a centrifugal separator, of an inlet pipe for conveyance to the separator of liquid to be separated, 'outlets from the centrifuge for respectively heavier and lighter separated liquids, and packing means with which outowing liquid contacts, of a return ow pipe connecting one of said liquid outlets with the separator inlet, a valve in said return flow pipe, a valve controlling the outlet for the-other liquid, and a regulating apparatus connected'with both -said valves and with said inlet pipeand adapted tolcontrol the operation of said valves by the pressure of liquid in such inlet pipe.

7. The combination with a centrifugal separarator, an inlet pipe forl conveyance to the separafor of liquid to be separated, outlets from the centrifuge for separated liquids, and packing means with which outiiowing liquid contacts, of means operable by the pressure in the inlet pipe to divert the liquids discharged through said outlets to the centrifuge inlet, said liquid diversion means comprising return iiow pipes connected with-the respective outlets and a funnel into which said diverted liquids dis/charge, so that return iiow liquids may stream in freevand visible jets into the funnel and preventing thestreaming of liquid from one outlet to the other.

8. The combination with a centrifuge provided with an inlet and an outlet and comprising packing means with which outowing liquid contacts, of a pipe adapted to convey ra cooling liquid and communicating with the packing means of the centrifuge, and means to maintain said pipe closed during normal flow toward the centrifuge of liquid to be treated and to open said pipe to admit cooling uid to the centrifuge when the input of liquid to be treated falls below a-desired minimum, said means comprising a housing having openings communicating respectively with said inlet, said cooling liquid pipe and said outlet, and means in said housing closing communi-l cation between the rsttwo openings and normally closing communication between the last two openings and operable, by a predetermined drop in pressure -in said inlet, to open communication between the last ltwo openings.

9. The combination with a centrifuge provided with an inlet and an outlet and comprising packing means with which outilowing liquid contacts, of a pipe adapted to convey a cooling liquid and communicating with the packing means of the centrifuge, and means to maintain said pipe closed during normal ow toward the centrifuge of liquid to be treated and to open said pipe to admit cooling iiuid to the centrifuge when the vinput of vliquid to be treated falls below a. desired minimum, said means comprising a. housing having openings communicating respectively with said inlet, said cooling liquid pipe and said outlet, means in said housing closing communication between the i'lrst two openings, and a spring tending to operate said means to open communication between the last two openings, said spring being prevented from so operating by the inlet pressure operating through the first opening unless said pressure drops below a predetermined minimum.

10. In combination with a centrifugal separator having packing means requiring cooling by liquid flowing through said separator and a primary pipe system normally open for flow to the separator inlet of liquid to be separated, a. secondary pipe system adapted to convey a cooling liquid in contact with said packing means and normally closedagainst any ow and means, operable by reduction of pressure in said primary system, to open said secondary system for cw until restoration of pressure in said primary system.

11`. 'I'he combination with a centrifugal separator provided with an inlet and an outlet and comprising packing means with which outflowing separated liquids contact, of a supply pipe adapted to convey liquids to be separated to said inlet, means adapted to divert a portion of one ofthe separated liquids to the inlet side of the centrifuge and to throttle the discharge of the other separated liquid, and means, controlled by the pressure of the liquid to be treated flowing to be treated is not being supplied thereto or is being supplied thereto at a subnormal rate below a predetermined minimum rate, said process comprising owing a cooling liquidY through said packing box during said period, owing the liquid to be treated toward the centrifuge, shutting oif saidowof cooling liquid while the liquid to he normal ow of the liquid to be treated, by the reduced pressure of the liquid to be treated flowing toward the centrifuge inlet.

13. In a centrifuge provided with an outlet for treated liquid and comprising packing means with which outflowing liquid contacts and a source of supply for liquid to be treated conn'ectedwith the centrifuge, the herein described means of preventing damage to said packing means while the centrifuge is operating during the' period when the liquid to be treated is not being supplied thereto or is ybeing supplied thereto at a subnormal rate below the predetermined rate, said means comprising a source of supply of cooling liquid and a connection therefrom to the centrifuge, a device operable to shut off the flow of cooling liquid to the centrifuge while the liquid to be treated is being supplied at not below said predetermined minimum rate, and means, controlled by the reduced pressure of the liquid to be treated owing toward the centrifuge during its said period of subnormal ow, to operate said device to allow flow of cooling liquidl to the i centrifuge.

14. The' combination with a centrifuge having packing members lliable to damage by excess heat, a closed feed passage and a closed discharge passage, of a cross passage through which discharged liquid is adapted to iiow from the discharge passage to the feed passage, and means, controlled by pressure of the liquid to be treated owing toward the centrifuge, to shut'o said flow through said cross passage while the liquid to bev/treated is being supplied at not below a. predetermined minimum -rate and to open said cross passage to said flow when the supply of liquid to be treated falls below said predetermined rate.

15. The combination with a centrifuge having packing members liable to damage by excess heat, a closed feed passage and a closed discharge passage, of a cross passage through-which discharged liquid is adapted to flow from the discharge passage to the feed passage, a valve controlling theow of liquid through said cross passage, and means, controlled by excess of pressure inthe feed passage over that in the dis charge passage, to hold said valve closed while the liquid to be treated is being supplied at a normal rate and to open said valve upon reduction of pressure-due to reduction of feed of liquid to be treated to allow an endless circulation of liquid through said passage and centrifuge to maintain said packing members cool.

16. The process of preventing overheating of the packing members of a closed centrifuge which comprises flowing liquid to be treated into said centrifuge and discharging centrifugally treated liquid therefrom and in the course of its said ow contacting liquid with said packing members, returning discharged liquid to the centrifuge when the ow of the liquid to be treated is arrested or reduced below a predetermined rate and utilizing the pressure of inowing liquid to be treated to arrest said return of discharged liquid during inflow of the liquid to be treated at not below said predetermined rate.

17. The process of preventing damage to the packing members of a closed centrifuge which comprises rflowing the liquid being centrifugally treated in contact with such members, discharging treated liquid independently of the inflow of liquid to be treated while said inflow is proceeding at a normal rate, returning discharged liquid to the centrifuge inlet when said inflow of liquid to be treated is reduced below the normal rate. and utilizing the pressure of inowing liquid to be treated to govern said discharge.

HANS OLOF LINDGREN. 

